1. Field of the Invention
The present invention relates to a positive photosensitive composition for use in the manufacturing processes of semiconductors such as IC and the like, liquid crystals, the manufacture of circuit substrates for thermal heads and the like, and other photo-fabrications, and a pattern-forming method using the same. More specifically, the invention relates to a positive photosensitive composition suitable for use in the case where far ultraviolet rays of 250 nm or less, preferably 220 nm or less, are used as exposure light sources, and electron beams are used as irradiation source, and a pattern-forming method using the same.
2. Description of the Related Art
Chemical amplification photosensitive compositions are pattern-forming materials capable of generating an acid at an exposed part upon irradiation with radiation such as far ultraviolet rays, changing the solubility in a developing solution between the irradiated part with the actinic radiation and the non-irradiated part by reaction with the acid as a catalyst, and forming a pattern on a substrate.
In a case where a KrF excimer laser is used as an exposure light source, resins having poly(hydroxystyrene) small in absorption in the region of 248 nm as a fundamental skeleton are mainly used, so that a good pattern having high sensitivity and high resolution can be formed as compared with conventional naphthoquinonediazide/novolak resins.
On the other hand, when a light source of a shorter wavelength, e.g., an ArF excimer laser (193 nm), is used as an exposure light source, even these chemical amplification photosensitive compositions are not sufficient, since compounds containing an aromatic group substantially show large absorption in the region of 193 nm.
Therefore, resists containing a resin having an alicyclic hydrocarbon structure for an ArF excimer laser have been developed. Various improvements have been tried in resists for an ArF excimer laser. For example, in JP-A-2005-331918, JP-A-2004-184637 and JP-A-2003-330192, various improvements of characteristics have been done in repeating units having an alicyclic acid-decomposable group by the introduction of repeating units having a spacer part between the main chain and the acid-decomposable group.
However, in forming a pattern having a line width of as fine as 100 nm or less, a line pattern formed falls down even if resolution performance is excellent, which causes a drawback such as falling down of a pattern leading to a defect in manufacturing a device, and the stability of performances to the change in exposure quantity (exposure latitude) is not sufficient.